Richard Frederic Evans; Historian of the D.C. Area

Richard Frederic Evans, 71, a ubiquitous volunteer who used his encyclopedic knowledge of Washington history to assist researchers, museums and thousands of tourists, died June 27 of congestive heart failure at his home in the District.

Mr. Evans, a professional engineer, spent more than three decades researching, preserving and sharing the rich past found within the halls and on the walls of Washington museums and historical societies.

"He was kind of like the living database," said a nephew, Bob Evans, who said his uncle continued volunteering until days before his death.

For at least 33 years at the Smithsonian Institution, Mr. Evans brought enthusiasm and knowledge to his work as docent at the Smithsonian Castle and a volunteer on the information and telephone desks, said Katherine Neill Ridgley, director of the Visitor Information and Associates' Reception Center.